1. Field of the Invention
This invention relates to light-sensitive imaging elements and particularly to photographic elements having a polyester film support with an adhesion promoting layer on at least one surface of the polyester support.
2. Description of Related Art
It is difficult to adhere photographic emulsions to oriented polyester supports, such as polyethylene terephthalate and polyethylene naphthalate. This problem is exacerbated by the conditions to which photographic elements are subjected; i.e., the adhesion must not fail in the raw and processed dry state, as well as when the film is wet during the development process.
Several subbing materials, such as poly(methyl acrylate-co-vinylidene chloride-co-itaconic acid) and poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid) disclosed in U.S. Pat. Nos. 3,201,249 and 3,143,421, respectively, provide the required adhesion when applied before orientation but are not as effective when applied on oriented support. The effectiveness of these adhesive materials may be enhanced by the use of swelling or attack agents such as resorcinol.
An alternative approach disclosed in U.S. Pat. No. 4,695,532 describes a discharged treated polyester film support having coated directly thereon a crosslinked layer of an aqueous vinyl acrylate copolymer and gelatin mixture. Although this system has good adhesion before processing, the adhesion performance is severely degraded by photographic developing solutions.
EP 0583787 A2 discloses the use of glow discharge treatment to enhance the adhesion of photographic elements. This treatment involves the use of high energy plasma under vacuum which requires specific equipment.
U.S. Pat. No. 5,378,592 discloses the use of a subbing layer (for photographic materials) that comprises a polyurethane latex cured with an epoxy compound or a dichloro-s-triazine derivative. It is not a self-crosslinkable polyurethane.
It is desirable to provide polyester film supports having improved wet and dry adhesion of hydrophilic colloid emulsions. It is also desirable to provide such supports that are free of photosensitive active materials.